The last few times I have bled my clutch, I have seen no improvement. What is the next thing to check? I have followed the Perfection Clutch Bleed video each time.
Note: A few years ago I did try installing a new master and line, but it didn't really improve things much

Basic symptoms:
Very tough to put into first and reverse. No slipping when driving. No abnormal noises. Driving performance and transmission SEEM good.

What I've done and see:

1. I do the full removal of the line, suspend and straighten for a bench bleed. Tap it up and down (a lot) and see zero bubbles coming to the surface in the reservoir. In this state, I have maybe 1/8" of push on the push rod. When I do push it, I get that very small amount of fluid pushing back into the reservoir and I see the bulging in the middle. I always think it's a bubble, but no such luck.
2. Once the line is back in and connected to the slave cylinder, I do a gravity bleed. My method has been press the clutch, open the valve as it purges a small amount of fluid, close the valve, release the clutch. Do that over and over.
3. Pulling the rubber cover to take a look at the slave, everything is dry and looks good. Pressing the clutch and it sure seems like I'm getting plenty of movement on the slave.
4. Everything back together and cleaned up, still have to jam it into gear.

Is there a logical next step?
Though I feel I'm following the steps strictly, what step am I maybe messing up that ruins the entire thing?
Is there any physical part of the system that could be bad that maybe I'm not aware of?
Will I ever be happy again?

 

The only thing that I did different was I went to Harbor Freight and bought the one man brake bleed system. It allows fluid to only go in one direction. Mine works fine now. You can watch the video on it it see if you think that it might work for you. Hope that this helps.

 

I am not sure exactly what you are doing to bench bleed the master cylinder. I found you can't bleed it without turning it upside down, press in on the piston until it is firm. Let up and keep pumping until it has no give to it. Otherwise, any trapped air just stays in there. You can do it in the vehicle, but you must disconnect it from the firewall. Gravity bleed of the slave works but is not the best way. If I have no one to help me, I push in on the clutch pedal and use a board that is cut to the right length to wedge in against something to hold the pedal down. then open the slave bleeder and close, then let up on the pedal. Repeat until no air comes out.

 

I'm bleeding the master by pulling the master and the entire line, hanging it up, inverting the cylinder and straightening the line so there are no pockets or places that don't lead up to the reservoir. Then tapping for several minutes. During this time I am also pumping the piston. And that is one of the times that confuses me. The piston is never soft, even at the beginning. And pumping it is not producing any bubbles. If I didn't know any better, the master and the line are totally bubble free and in an ideal condition. When it comes to bleeding the slave, I do exactly as you do. Press the clutch in, jam it down with a board, open the release valve, close it back up, then release the clutch. Repeat over and over. And like I said, with basic visual of the slave, there is nice movement on it when the clutch gets pushed in. Everything SEEMS to be functioning properly and engaging the slave as it should. Yet putting it into gear is a struggle. Like my gear shifter, I'm stuck.

 

Sounds like you are doing everything right. If you disconnect the quick connect to the slave, do you have a hard clutch pedal?

I have heard of the firewall getting cracked and deflecting when the pedal is depressed resulting in not getting a full release of the pressure plate. I think with all the times you have been in there you would have seen it if that was happening though.

There is something else that can cause this. The pilot bearing in the flywheel has needle bearings that can wear and fall out of place. That ends up binding the input shaft to the transmission. So, even when you push in on the clutch the input shaft is trying to spin from the binding pilot bearing. I had this happen one time when my Ranger tried to take off while sitting at a stop light with the clutch pedal pushed in. I had been having random times when I could not it into gear and had to shut off the engine to get it in gear then start with it in gear. That is why I had it in gear while stopped at the stoplight. Once it tried to take off with the clutch in, I realized it must be the pilot bearing. When I pulled the transmission, many of the pilot bearing needles fell out. I don't know if there is a way to diagnose that without having to pull the transmission.

Unless there is something radically wrong with the clutch disc or pressure plate, I can't think of anything else that would cause this issue. A ballooning flex line could cause it, but you have replaced that with the master cylinder.